'Are you a Jewess?" asked Sarah, her eyes lighting up with hope. I found myself apologising that I was not. Here, in Cochin's Jew Town, octogenarian Sarah is one of only 10 remaining white Paradesi Jews, whose ancestors arrived in Kerala in the 16th century, fleeing the Inquisition in Europe. Little is left of this once powerful community, feted by the local rulers. Their numbers were eroded when many emigrated to Israel in 1948 and those who were left refused to integrate with their neighbours, the black Malabari Jews.

Today, the narrow picturesque streets of Jew Town – once a busy port for the spice trade and home of the famous Pepper Exchange – are a major tourist attraction, fast approaching museum status. Sarah sits, like a living exhibit, in colourful floral frock behind a grill wrought with Stars of David in her lurid green house on Synagogue Lane, from which she sells her Jewish-themed embroideries. All around her, former Paradesi homes and godowns are occupied by Kashmiri traders, with their ubiquitous shawls and jewellery, and dubious antiques emporia. Hunt judiciously, though, and there are still some wonderful pieces to be found.

I made my way down the lane to the eponymous synagogue. Built in 1568, the oldest continuously functioning synagogue in the British Commonwealth, it is a small jewel, its coffered ceiling hung with mismatched lamps of Belgian and Murano glass, the floor paved with 1,100 blue-and-white Chinese tiles. Legend has it the tiles were intended for the Maharaja's Hindu temple in 1762. A local, on seeing the beautiful tiles, apparently persuaded the Maharaja that ingredients in their manufacture included sacred cows' blood. The ruse had the intended effect. The horrified Maharaja rejected the tiles, which found their way to their present home.

Ironically, however, there are no longer enough men within the community to form the necessary quorum for Sabbath prayers. Yaheh, who sells tickets at the synagogue entrance, is in her thirties and the youngest member of the community. It must be a uniquely lonely experience to know that she is destined to be the last of the Paradesis.

Kerala is a curious land, where churches, synagogues, temples and mosques celebrate in happy proximity. When the missionaries arrived, following the landing in Calicut of Vasco da Gama in 1498, they were surprised to find Orthodox Christianity – supposedly brought to Kerala by St Thomas in AD 52 – already established. They built their Catholic churches, which were successively appropriated by the Dutch and British colonists, the resulting mishmash of architectural styles – Portuguese arches, Dutch wooden balconies, British colonnades – contributing to Cochin's distinctive character.

Meanwhile, among the vestiges of Kerala's colonial past, boys play cricket on parade grounds, fishermen sell their catch along a shoreline dentellated with cantilevered Chinese fishing nets, patients queue for the potions of Ayurvedic practitioners in the shade of umbrella trees, and a snake-charmer entertains passers-by.

"When we first arrived in Kerala in the early Nineties, there was nowhere to stay," says Joerg Drechsel, owner of the proto-boutique hotel, Malabar House, a restored Dutch mansion and the trendiest joint in town. "And the houseboat phenomenon only got going 20 years ago."

For most, Kerala is synonymous with the backwaters – a network of lagoons and canals covering 1,235 sq miles, between the Arabian Sea and the uplands of the Western Ghats.

But before exploring these byways, we headed through coconut and pineapple plantations, up into the mountains, to investigate a wholly different world, some 60 miles (100km) away.

We climbed through lush forests into a granite landscape, cliffs glistening with waterfalls, to reach Munnar, whose misty hills are mottled with neat clumps of tea bushes. Women were at work, clipping the bushes with shears and collecting the precious leaves. Herds of wild elephant that inhabit the forests above occasionally make their way through the plantations to the river below – much to the consternation of the workers.

A region of huge biodiversity, it is a paradise for plant and bird- lovers, home to the rare Nilgiri tahr – a kind of oversized goat – and the even rarer Neelakurinji plant, which flowers once every 12 years to carpet the slopes in purple blossoms (next flowering, October 2018). Descending to Periyar, at 3,281ft, tea plantations give way to fragrant spice gardens, where guides explain the medicinal uses of different plants. This, after all, is Kerala's spice capital, where streets are lined with shops selling exotic spice, essential oils and Ayurvedic remedies. At the Shalimar Spice Garden, I had an Ayurvedic massage administered by a man in an apron and in front of a smoking fire, which left me feeling like beef being marinated for a barbecue.

The region's highlight was to be found hidden in the middle of nowhere. Serenity (by name and by nature) is an exquisite retreat in the tiny village of Kanam. Here, in the middle of a rubber plantation, one can relax to the gentle pace of village life aboard Lakshmi, an exceptionally well-mannered elephant, rescued from a circus. She took me through a village grown prosperous through rubber, past saw mills and toddy factories, to the river, for her bath. In a classic example of the hunter hunted, locals stopped with flashing smiles and waved, asking permission to take my photograph on their mobile phones.

We reached the backwaters, where the new Purity – the latest in the stable of the Malabar Escapes chain of boutique hotels – has just opened its doors on the lapping shores of Lake Vembanad. I cruised the lake aboard the MV Apsara, transferring to a chikara – a kind of covered longboat – to negotiate the narrow canals between the sunken rice paddies.

On the raised dykes that separate paddy from canal, a whole world balanced: schools, hospital, churches; and the houses of farmers and fishermen, whose wives busied themselves washing pans and clothes in the murky waters, unperturbed by our passage. Kingfishers darted around us, and Brahmini eagles soared overhead as dusk fell and fishermen took to the lake to cast their nets for the night. No visit to Kerala is complete without a stay on its wild, 360-mile coastline. At Kovalam, Vivanta by Taj cloaks a hillside that overlooks a perfect coconut lagoon. I dined on the freshest seafood on the beach as moonlight shimmered on the roaring surf of the Arabian Sea. Even the breeze conspired to create perfection, keeping the nocturnal mosquitoes at bay.